By late March 2020, primary and secondary schools closed in nearly every country as the coronavirus pandemic unfolded.
According to UNESCO, it affected more than 1.5 billion learners.
Educators in many places later shifted to remote teaching hoping to rescue the academic year.
Since then some countries have cautiously reopened school while others do not plan to resume in-person classes until 2021.
But various challenge of reopening schools remain there. Schools have struggled with what to do if teachers or students test positive.
In August, Just two weeks after schools reopened in the United States, a total of 97,000 students have tested positive for the novel coronavirus.
In case of guidelines, different states are following different rules.
For example, Florida also left it up to districts to decide whether masks should be worn by students and staffers. Some require it, but many don't,
When Israel reopened schools in May, the government did not require schools to follow social-distancing guidelines for long, and many classrooms returned to full size with around forty students.
Since then, more than two thousand people have tested positive throughout the country's education system and at least one teacher has died. In Israel and other countries, some parents and guardians have refused to send their children to school out of concern for both their child's safety and their own.
Schools in Germany, where infection rates are low, have taken a different approach, keeping classes running and forcing only close contacts of the infected person to quarantine.
Reopening schools is also expensive. Health experts have called on schools to guarantee they have enough personal protective equipment (PPE), such as masks and face shields, for students and teachers; cleaning supplies; and other safety materials, including plastic barriers, the costs of which can add up.
Some schools have hired more teachers because of smaller class sizes, and others have paid to improve their ventilation systems and build handwashing stations.
While primary and secondary schools in the United States have so far received $13.5 billion in federal relief, education policy researchers say it's not enough for schools that were already struggling with funding. One report estimates that implementing precautions will cost $1.8 million for a US school district with around 3,200 students. For example, reopening all of Maine's public schools will cost an estimated $328 million.
Pandemic safeguards have also put special burdens on educators. Restrictions have made it difficult to promote collaborative and engaging learning, especially for younger students.
In addition to fearing for their own health, teachers in schools that follow a hybrid model of in-person and online learning face the added stress of preparing lesson plans for both approaches.